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Thread: Where are we in the universe?

  1. #1 Where are we in the universe? 
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    IS there a map where we can see where we are. I'm having trouble understanding things. If a big bang did occur, would the start of the universe be centralized, with galaxies expanding outward equally, Or would it take on a random form and not be completely spherical in expansion. I hear they are looking for the start of the universe, but what is beyond the newest stars, If indeed this is the way the universe works.


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    Moderator Moderator Dishmaster's Avatar
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    There is no such thing like a centre of the universe, because it has no edge. An often used analogy compares the expansion of space in 3D with the expansion of the surface of an inflating balloon in 2D. It makes no sense to look for the centre of the balloon's expansion on the surface. The general paradigm is that the universe is homogeneous and isotropic. This means that on average the universe looks the same in every direction and in general has an identical shape and structure everywhere.

    However, one can say that the sun is located about 8000 pc away from the centre of the Milky Way which again is part of a cluster of galaxies.


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  4. #3  
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    If the big bang happened in three dimensions, there would be a centre of the universe. However, they claim it happened in four physical dimensions so similar to a balloon where the universe is the skin. The $64 question is what is inside causing the expansion and would it be the end of the universe if we made a 4D explosion which punctured the 3D skin.

    The big bang is probably nonsense for many reasons. It calcifies discussion because the BB-ers say: thebbisit so you're wrong if you say otherwise. A bit like arguing with a creationist.

    The universe is probably of unknown size and age. The CMB is probably a haze caused by cosmic distance. There could be a trillion light years and more beyond it. Until we know a lot more, we cannot know where we are. Light is very slow in cosmic terms so our view of the universe is increasingly outdated the further we look into space.

    If you have decent internet, check out the cosmic zoom:

    http://www.youtube.com/watch?v=iMV_zDQaq9o


    It's entertaining if nothing else.
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  5. #4  
    Forum Senior Booms's Avatar
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    Quote Originally Posted by Dishmaster
    There is no such thing like a centre of the universe, because it has no edge.

    of course there can be a centre with no edge, we have points marked all thought the universe just because we don't have a set boundary doesn't mean we can't find the centre
    It's not how many questions you ask, but the answers you get - Booms

    This is the Acadamy of Science! we don't need to 'prove' anything!
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  6. #5  
    Moderator Moderator Dishmaster's Avatar
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    Quote Originally Posted by Booms
    Quote Originally Posted by Dishmaster
    There is no such thing like a centre of the universe, because it has no edge.

    of course there can be a centre with no edge, we have points marked all thought the universe just because we don't have a set boundary doesn't mean we can't find the centre
    Huh? The centre is a point with the shortest distance to the edges. So how can there be a centre without a boundary?
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  7. #6  
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    Quote Originally Posted by Dishmaster
    It makes no sense to look for the centre
    Alternately, you could say every point is a center, if a center is the point most surrounded by a volume. Perhaps that's equally silly, but it's how I see it.
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    Forum Senior miomaz's Avatar
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    Quote Originally Posted by Dishmaster
    Quote Originally Posted by Booms
    Quote Originally Posted by Dishmaster
    There is no such thing like a centre of the universe, because it has no edge.

    of course there can be a centre with no edge, we have points marked all thought the universe just because we don't have a set boundary doesn't mean we can't find the centre
    Huh? The centre is a point with the shortest distance to the edges. So how can there be a centre without a boundary?
    I understand what Dishmaster wishes to express, but, for example, our earth is vaguely round and therefore has no edges. This fact contradicts with your argument, we have maps of earth with or without edges.

    @pong
    I think a way of defining 'center' is though relativity of objects: for instance 4 spheres at random distance to each other, one can calculate the 'center' by adding the x(1,2,3,4) y(1,2,3,4) and z(1,2,3,4) -values separately and dividing thouse numbers by 4 to get the center x,y,z values of those four spheres.
    I think a possible way to define the center of the universe would be to roughly do this with all galaxies (which should be quite hard)
    I haven't come to fight my word, but to find the truth.
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  9. #8  
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    Why should the universe expand in four physical dimensions? It shouldn't. A 3D expansion, allowing for some magic so that it does not obey the laws of gravity and become a black hole, would suggest that it would end up as an ever expanding shell, moving away from a central point. However such a shell would be "very thin" and detectable to us.
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